1. Field of the Invention
This invention relates to systems for control of computer track balls, and in particular pertains to a device for controlling track ball movement for enabling sensing of features shown on a computer screen, for example, height of features on a topographic map, for restricting movement of the cursor on the screen in certain screen areas, and for forcing cursor movement in a particular screen direction.
2. Description of the Related Art
Computers having movable input devices, known as track balls or mice, enable movement of a cursor on the computer display device (screen) without requiring operator knowledge of programming or advanced keyboard commands. Standard track balls are configured so that motion of the cursor on the computer screen is controlled by movements of the track ball in a pathway that may be defined by a series of X,Y coordinates. As shown in FIG. 1, the ball 20 of prior track ball device 22 is mounted in a hole 24 in a track ball cover 26 so that it rotates freely on a mounting base 28 in response to pressure of one or more fingers on the portion of the ball above the hole. Between the cover 26 and base 28, there is generally a pick-up wheel 94 on one side of the ball which is in contact with the track ball 20 for indication of the X-coordinate and another pick-up wheel 94 on another side of the ball, 90.degree. from the first pick-up wheel, and also in contact with the track ball, for indication of the Y-coordinate. An encoder 32 for each direction translates the physical movement of the track ball into movement of the cursor on the screen. Each encoder 32 is a wheel having slots 34. Every time an open slot 34 allows light to pass, a small voltage pulse is generated by an associated photo diode (not shown). The angle turned through by the wheel may be determined by a counter counting the voltage pulses. There are usually two photo diode/light source assemblies, so that clockwise movement and counterclockwise movement of the encoder may be distinguished. An idler bearing (not shown) is placed beneath the ball to support it. The fact that mice connected to computers are analogous to track balls in both structure and function means that the aspects of the invention discussed herein are directly usable or are adaptable by those of skill in the art for use with mice as well as with track balls.
The ease of movement of the cursor at any location on the visible screen, or to areas off the screen, can result in problems in placing and keeping the cursor in a desired position and in keeping the cursor from particular areas of the screen. In addition, it is often difficult to be sure where the cursor is located on the screen. In a number of different types of screen displays, it also would be educational or otherwise desirable to be able to sense vertical movement of the track ball as the cursor is moved across features shown on the screen, for example, across lines, or across typographical features on a map.
Examples of patents for controlling cursor movement and for previously known feedback mechanisms for track balls include the patents of Luque (U.S. Pat. No. 4,538,476); Whetstone et al. (U.S. Pat. No. 4,550,316); and Soma et al. (U.S. Pat. No. 4,739,315).
The patent of Solhjell (U.S. Pat. No. 5,162,780) provides a Trackball for Data Entry and Control with Optimized Height in which the vertical height of the ball may be adjusted relative to the housing to suit an operator's preference. There is no suggestion of adjusting the track ball height in relation to features on the computer screen.
Efforts to address one or more of these concerns are found in the patents of Affinito (U.S. Pat. No. 4,868,549 for a Feedback Mouse which generates resistance-to-motion feedback to the mouse which may be physically perceived by the user); Culver (U.S. Pat. No. 4,896,554 for a Multifunctional Tactile Manipulatable Control provides an operator with an enhanced tactile sense of the action of the control mechanism which includes a rotating cylinder journalled in a movable bar slidable in a grove in a deflectable support rack); Hedtke (U.S. Pat. No. 4,952,081 for Manual Rotary Sphere Control of an Electronic Equipment with Touch Sensing Scale Marks, which has controllable braking devices of the control sphere used for tape recording and playback); Arita et al (U.S. Pat. No. 5,432,530 for a Pointing Device and Method of Control of Same, which provides a means of switching from positional control for controlling the position of a cursor to speed control for controlling the speed of movement of the cursor); and Kelso (U.S. Pat. No. 5,470,232) for a Reconfigurable Aircraft Stick Control and Method for Connecting and Removing Stick Control from Aircraft Simulator, which enables pitch and roll of an aircraft to be simulated).
The patent of Good (U.S. Pat. No. 5,185,561) for a Torque Motor as a Tactile Feedback Device in a Computer System uses as a computer input device, a motor in a hand held housing, a shaft extending from the motor to be rotated by hand and provide torque to a user's hand, a position indicator for output to a computer indicating the shaft rotational position, and an input to the motor for controlling torque applied to the shaft by the motor from a computer output. The torque motor and shaft may be configured as the shaft of a conventional joystick so that the shaft can be manipulated to manipulate the display and could be twisted for rotational manipulation and torque feedback.
It is therefore an object of the invention to provide a device which allows a track ball to be interactive and provide physical feedback from the computer to the user, targeted at the user's fingertips, to provide various sensations that are synchronized or related to the visual and/or auditory environment of the software. Thus, the invention enables manipulation of a virtual environment generated by the computer to enhance interaction with the virtual environment and provide tactile feedback to the user.
It is a further object of the invention to provide a device which can be used to enhance the effect of a video game, provide additional information in a computer-assisted design (CAD) or virtual reality application, or enable the physically impaired to receive information from the software that might not otherwise be available to them.
It is a further object of the invention to provide a track ball control system for a computer, having at least one track ball regulator for providing physical control of a track ball position in response to signals which are generated depending on the location of the cursor, so that the track ball has a resultant change in movement in response to the signals which is distinct from and not dependent on the direct control of the track ball by the operator.
Other objects and advantages will be more fully apparent from the following disclosure and appended claims.